modern - varsity field · location and extraction of resources has have prospered ... following...
Post on 29-Apr-2018
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Modern society depends on the availability of renewable as well as non‐renewable resources Renewable Resources: A resource such as timber, water, or air, that is naturally recycled or recycled by artificial processes within a time frame useful for people Non‐renewable Resources: A resource that is cycled so slowly by natural Earth processes that once used, it is essentially not going to be made available within any useful time framework Therefore, what partially differentiates renewable and non‐renewable resources is their availability within the human time framework
The availability of resources is one measure of a society’s wealth Those that have been most successful in
location and extraction of resources has have prospered
Modern technological civilization CANNOT exist without material resources Materials Management: In waste management, methods consistent with the ideal of industrial ecology, making better use of materials and leading to more sustainable use of materials Industrial Ecology: The process of designing industrial systems to behave more like ecosystems where waste from one part of the system is used as a resource in another part
The goal of MM pursued in the following ways:a) Eliminate subsidies for extracting virgin
materials such as minerals, oil, and timber
b) Establish ‘green building’ incentives to encourage the use of recycled‐content materials
c) Assess financial penalties for production that uses poor materials‐management practices
d) Provide financial incentives for industrial processes/products that benefit the environment
e) Provide incentives for individuals/industries/agriculture to develop MM strategies that reduce/eliminate waste by using it as raw materials for other process/products (industrial ecology)
Minerals = valuable, non‐renewable heritage from our geologic past Ore deposit: Earth minerals in which metals exist in high concentrations, sufficient to be mined Elements not evenly distributed in crust (9 elements account for 99%): Oxygen (45.2%) Silicon (27.2%) Aluminium (8.0%) Iron (5.8%) Calcium (5.1%) Magnesium (2.8%) Sodium (2.3%) Potassium (1.7%) Titanium (0.9%)
Mineral Reserves (known to exist but not yet mined)
World Rank Production (per year)
Rand Value
Manganese 4 bt 1 3.6 mt R 3b
Titanium 146 mt 2 1 mt R 600 m
Nickel 12 mt 6 37 000t R 2 b
Copper 13 mt 14 0.14 mt R 1.6 b
Iron 1.5 bt 9 34 mt R 3 b
Coal 55 bt 5 224 mt R 20 b
South Africa’s Mineral Reserves
Sedimentary processes can lead to the concentration of material resources sufficient for extraction Gravel, sand, clay
Biological processes Lead to the formation of phosphate (e.g.
guano), iron deposits
Evaporites Rivers and streams carry dissolved
minerals into oceans/seas These in turn can get isolated by tectonic
activity As they dry up, minerals precipitate and
can be extracted later on (e.g. table salt)
Weathering Can concentrate minerals in soil Combined with erosion lead to
development of SA’s gold reserves
Estimating how much is left, combined with consumption rates, provides estimates of how long they will last Motivation to make them last as long as possible (i.e. MM) Mineral Resources: Elements, chemical compounds, minerals or rocks concentrated in a form that can be extracted to obtain a usable commodity Mineral Reserves: Concentrations that at the time of evaluation can be legally and economically extracted as a commodity that can be sold as a profit) Legal component includes environmental
legislation
Mineral Categories1. Elements for metal production and
technologya) Abundant: iron, aluminium, chromiumb) Scarce: copper, lead, zinc
2. Building materials Stone, gravel, sand etc.
3. Minerals for agriculture e.g. phosphates (fertilizer)
Rates of use Na, Fe: 100 – 1000 mt/y N, S, K, Ca: 10 – 100 mt/y Zn, Cu, Al, Pb: 3 – 10 mt/y Au, Ag: <10 00 mt/y
At some point costs of extraction > value of mineral: Find more resources Recycle and reuse what has already been
obtained Reduce consumption Find substitute
Influence of economic, political or environmental factors Can make importing more desirable
Environmental Exploration has minimal impact (if done
with consideration) Mining and processing have considerable
impacts on land, water, air, & living organisms Open pit vs. underground mines
Using lower grades of ore causes more damage Higher grades usually extracted first
(future implications) Environmental degradation extends
beyond immediate vicinity of activity
Social Rapid influx of workers into areas Increase population size &
concentration Closing of mines Ghost towns
Price of minerals/materials Affects livelihood of communities Increase in price influenced by
environmental regulations (environmental economics)
Minimizing Impacts1. Reclaiming areas disturbed by mines2. Stabilizing soils containing metals to
minimize release into environment3. Controlling air emissions4. Treating contaminated water before it
leaves the mining site or treating water that has left the mining site
5. Treating waste on site and offsite6. Practicing the three R’s of waste
managementa) Reduce the amount of waste
producedb) Reuse waste as much as possiblec) Maximize Recycling opportunities
First Century of Industrial Revolution Dilute and disperse Easy disposal of waste in a river Tragedy of commons
As industrial areas expanded Concentrate and contain Containment not always achieved Acid mine drainage Dust pollution from tailings
NIMBY (Not In My Back Yard)
Environmentally correct approach Treating waste as a resource Industrial ecology Zero waste? Pollution taxes (Env Econ) ‘Pay as you throw’ (Env Econ)
Integrated Waste Management: Set of management alternatives including reuse, source reduction, recycling, composting, landfill, incineration Ultimate goal of the three R’s of IWN is to reduce the amount of urban and other wastes that need to be disposed of landfills, incinerators and other waste management facilities Iron, aluminium and copper have been recycled for many years and continues to be Iron and steel recycled in large volumes for two reasons:1. Huge market2. Large environmental burden for failing to
do so
Recycling of human waste Fertilizers Problems with pathogens, harmful chemicals
etc.
1. Onsite disposal Garbage disposal device installed under
sink (Not so common in SA) Food wastes enter sewage system for
treatment at sewage plants
2. Composting A biochemical process in which organic
materials, such as lawn clippings, compose to a rich soil like material
Drawback of waste separation before hand
Plant debris treated by herbicides may introduce harmful chemicals into environment (due to waste concentration)
3. Incineration Burns combustible waste at temperatures
high enough to consume all combustible material (900 ‐ 1000°C) leaving only ash and non‐combustibles for the landfill
Can supplement as fuel for generation of electricity
Drawbacks Air pollution, toxic ash
4. Open dumps Poorly controlled landfills Refuse piled up and left uncovered Common in rural areas of SA
5. Sanitary landfills A method of disposal of solid waste
without creating a nuisance or hazard to public health or safety.
Highly engineered structures with multiple barriers and collection systems to minimize environmental problems
Idea behind it: Confine waste to the smallest practical
area Reduce it to the smallest practical
volume Cover it with a layer of compacted soil
at the end of each day or more frequently if needed
5. Sanitary landfills (Issues) Leachate Site selection NIMBY Environmental considerations
Monitoring of pollution levels essential Ways pollution can enter environment:
a) Methane, ammonia, hydrogen sulphide and nitrogen gasses can be produced in landfill and enter atmosphere
b) Retaining of heavy metals in soil (chromium, lead)
c) Soluble minerals (chloride, nitrate) can enter groundwater
d) Surface runoff picking up leachate and transporting it to rivers
e) Uptake of heavy metals by plants growing on landfill (enters food web)
f) Toxic residue on plant material (herbicides) returned to soil
g) Contamination of streams by surface runoff and groundwater contamination
h) Transport of material by wind to other areas
Oceans have long been dumping grounds for many types of waste Industrial, construction, hazardous, urban Tragedy of the commons
Contributes to problem of ocean pollution Impact on marine ecosystems Death or retarded growth, vitality, and
reproductively of marine organisms Impacts on fisheries
Reduction of oxygen levels necessary for marine life due to increased BOD (biological oxygen demand)
Eutrophication Habitat change
Ways to stop generating so much waste, rather than to dispose of it or manage it Part of materials management
1. Purchasing the proper amount of raw materials so that no excess remains to dispose of
2. Exercising better control of materials used in manufacturing processes so that less waste is produced
3. Substituting nontoxic chemicals for hazardous or toxic materials currently used
4. Improving engineering and design of manufacturing processes so less waste is produced
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